SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1bc2617164f136ed47578d54c86da230c7a5fb584923dc48538f954b082b6a17' 
  AND token = '3ywpxMZbA+U7wHILo6IBVpHLS/8V1A7XhnXeOlovQKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}